This invention relates to a method of photometrically analyzing a liquid sample in a centrifuge rotor and an analytical instrument for performing the same method.
The application of photometry to a quantitative or qualitative analysis of a liquid mixture of a sample and a reagent is now quite familiar as represented by examination of human blood serum in the diagnosis of disease as well as for research purposes.
Also it is known to perform a photometrical analysis or examination of a liquid sample by utilizing a centrifuge rotor assembly in which the sample and a reagent are forced to flow into a chamber defined by transparent walls and mix therein by the action of centrifugal force. For example, U.S. Pat. Nos. 3,555,284 and 3,586,484 disclose photometric analyzers of this type. As an inconvenience to the users of such analyzers, cleaning of the interior of the centrifuge rotor after completion of a run, or a series of runs, of experiment (in preparation for a next experiment on a different kind of sample) needs to be performed by detaching the rotor from a drive motor portion of the instrument. Accordingly the cleaning operation requires much time and labor, and it is inevitable that the preceding and succeeding runs are performed with a considerably long interval of time.
As anoter inconvenience of an analyzer of the above described type when the liquid sample is a human blood serum, as an example, there is the need of preparing the sample by centrifugal separation of human blood into blood clots and serum by means of another centrifuge. This pretreatment takes considerable time and labor, and there arises a necessity for careful storage of the prepared serum samples which are liable to undergo changes in biochemical properties.